Seam Welding

Questions and Answers

Seam welding can involve large amount of power especially in a continuous seam weld. This generates a lot of heat which must be removed. The weld wheels are cooled through the hub that attaches them to the machine. Unfortunately this can be a long distance from the actual weld face. Just as in spot welding we need cooling near the face to help maintain the wheel integrity. In higher heat applications external water may be required. Water tubes are installed on both sides of the wheel top and bottom and cool water is spray on the wheel and weld area. This of course can be very messy but necessary for some applications.

Seam welding will generally use the same alloys as spot welding. The higher conductivity lower strength workpieces will be welded using Class 2 and the stronger work pieces will use Class 3. As in the case of spot RWMA Class 2 is the most used product for seam welding. Most seam welding wheels are ideally cross forged to break up the original cast billet grain structure. There are two schools of thought on this forging. One is to forge blanks after being sliced from a cast billet. The other is to forge the cast billet then slice the blank. Both processes break up cast structure but to different degrees. The individual forged blank process will inherently cost more since you forge each blank individually. If you have a difficult heavy wheel wear application you might want to consider paying the extra dollars.
Some wheels are made by cutting ends off rod and others by cutting out of plate. Neither of these products would be expected to hold up in heavy duty applications.

Electrode face mushrooming is the normal wear mechanism of a spot welding electrode. To slow this process or prevent excessive mushrooming one must control several factors in the welding process.

 Mushroomed electrode

EXTREME MUSHROOMING

Class 3 material is a designation of the Resistannce Welding Manufacturers Alliance (RWMA).  It describes a group of copper alloys with excellent strength and good electrical conductibity.  Class 3 is often used to weld stainless steel, nickel alloys and other highly resistive - strong materials that require high weld forces.

bar stock

Class 3 Bar Stock

Class 2 material is a designation of the Resistance Welding Manufacturers Alliance (RWMA).  This is a group of copper alloys with high strength and electrical conductivity.  Class 2 is the most used material in the resistance welding industry.  As electrodes it is used for welding bare and coated steels.

bar stock

Class 2 Bar Stock

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